Immunocytochemistry showed homologous recombination was abrogated in NBS(-/-) and ATM(-/-) fibroblasts, compromised in Fanconi anemia and normal in Bloom's syndrome cells in response to poly ADP-ribose polymerase inhibitors.
The proteins involved in FA act coordinately in the cellular response to DNA cross-links in a pathway that has been shown to interact physically or functionally with a variety of other proteins involved in DNA repair or cell cycle control, notably BRCA1, Rad51,ATM,ATR, and Nbs1.
Mutations in ATM, NBS1, MRE11, BLM, WRN, and FANCD2 are responsible for ataxia telangiectasia (AT), Nijmegen breakage syndrome, AT-like disorder, Bloom and Werner syndrome, and Fanconi anemia group D2, respectively.